When they hibernate, the crank bears a little more down on the oil seal than when it is running. An old seal in an old engine tends to lose its resilience and doesn't come back up right where it should, so you'd tend to get a little oil past the seal. Nothing serious, but it will not cure itself - you'll need a new seal sometime.
Oil light flickering at idle is no big deal - could be touchy switch, runny oil, worn bearings, worn oil pump, but likely a combination of circumstances. Mine always flickers after a long run on the expressway - been doing it for years. If it bothers you, crank the idle up a tad - hahahahaha.
You would probably be safe driving it till it gets worse and the light stays on - not flickers - at idle. Next oil change check the screen/oil sump plate carefully for any signs of coppery bearing material - then you'll KNOW it's time for a major.
Stick on an oil pressure gauge instead of just the switch if you really want to know what the oil pressure is doing. Check your manual for the correct running pressure for your engine.
When you do rebuild it, change the cam to one with a deep dished center if it hasn't been done already, and then you have room for one of the newer, deeper, higher volume oil pumps. I just did this to my neighbour's 1200 - but mostly cause his camshaft gear rivets were loose on the shaft, and I had a spare, newer type one sitting in the heap.
If it were me, I'd drop the engine down, fix the rumble or change the bearing, whatever if it was bad, and change the oil seal - or not, since it means pulling the flywheel off - and just drive it for a while longer.